Photovoltaic system, inverter, and direct current electric arc detection method

Patent metadata

Field	Value
Publication number	US-2023071656-A1
Application number	US-202217940191-A
Country	US
Kind code	A1
Filing date	Sep 8, 2022
Priority date	Sep 9, 2021
Publication date	Mar 9, 2023
Grant date	—

Abstract

A photovoltaic system, an inverter, and a direct current electric arc detection method. The system includes an inverter, a controller, and at least two converters. When detecting an electric arc, the controller controls an input current of the inverter to decrease to extinguish the arc. After the arc is extinguished, the controller controls an output voltage of at least one photovoltaic string to decrease to a first preset voltage, where the first preset voltage is less than an input voltage of the inverter when the electric arc is detected, or controls a maximum value of an output current of the at least one photovoltaic string to be a second preset current, where the second preset current is less than the input current of the inverter when the electric arc is detected. In the foregoing two recovery manners, no electric arc recurs.

First claim

1 . A photovoltaic system, comprising
an inverter, wherein an input terminal of the inverter is configured to connect to at least one photovoltaic string, each photovoltaic string of the at least one photovoltaic string comprises at least one converter and a photovoltaic module corresponding to each respective converter, and an input terminal of each respective converter is connected to the corresponding photovoltaic module; and a controller, wherein the controller is configured to: when an electric arc is detected in the photovoltaic system, control an input current of the inverter to decrease to extinguish the arc; and after the arc is extinguished, control an output voltage of the at least one photovoltaic string to decrease to a first preset voltage, wherein the first preset voltage is less than an input voltage of the inverter when the electric arc is detected; or control a maximum value of an output current of the at least one photovoltaic string to be a first preset current, wherein the first preset current is less than the input current of the inverter when the electric arc is detected.

2 . The photovoltaic system according to claim 1 , wherein the controller is further configured to increase the input current of the inverter after controlling the output voltage of the at least one photovoltaic string to decrease to the first preset voltage.

3 . The photovoltaic system according to claim 2 , wherein the controller is further configured to increase the input current of the inverter to the input current of the inverter when the electric arc is detected.

4 . The photovoltaic system according to claim 1 , wherein the controller is further configured to decrease the input voltage of the inverter after controlling the maximum value of the output current of the at least one photovoltaic string to be the first preset current.

5 . The photovoltaic system according to claim 4 , wherein the controller is further configured to decrease the input voltage of the inverter to the input voltage of the inverter when the electric arc is detected.

6 . The photovoltaic system according to claim 3 , wherein the controller is further configured to: when no electric arc is detected within a preset time period after increasing the input current of the inverter to the input current of the inverter when the electric arc is detected, skip controlling the output voltage of the at least one photovoltaic string to decrease to the first preset voltage.

7 . The photovoltaic system according to claim 5 , wherein the controller is further configured to: when no electric arc is detected within a preset time period after decreasing the input voltage of the inverter to the input voltage of the inverter when the electric arc is detected, skip controlling the maximum value of the output current of the at least one photovoltaic string to be the first preset current.

8 . The photovoltaic system according to claim 1 , wherein each of the at least one photovoltaic string comprises at least two converters, an input terminal of each of the at least two converters is connected to the corresponding photovoltaic module, and output terminals of the at least two converters are connected in series and connected to the input terminal of the inverter.

9 . The photovoltaic system according to claim 8 , wherein the controller is further configured to control an output voltage of each converter in the at least one photovoltaic string to decrease, so that the output voltage of the at least one photovoltaic string decreases to the first preset voltage.

10 . The photovoltaic system according to claim 9 , wherein the controller is further configured to control, based on the first preset voltage V and a quantity n of converters comprised in the at least one photovoltaic string, all output voltages of n converters to decrease to V/n, wherein n is a positive integer greater than or equal to 2.

11 . The photovoltaic system according to claim 10 , wherein the controller is an inverter controller;
the inverter controller is further configured to send a voltage control instruction to the n converters in the at least one photovoltaic string, and the voltage control instruction carries V/n; and the n converters are configured to control, based on V/n carried in the voltage control instruction, the output voltages to be V/n.

12 . The photovoltaic system according to claim 8 , wherein the controller is further configured to send a current control instruction to each converter in the at least one photovoltaic string, to control an output current of each converter in the at least one photovoltaic string to be less than or equal to the first preset current.

13 . The photovoltaic system according to claim 12 , wherein the inverter controller is further configured to send the voltage control instruction or the current control instruction to the n converters through 485, PLC, WIFI, or ZigBee, to control a voltage output or current output of the converter.

14 . An inverter, comprising
an inverter controller; and a power conversion circuit, wherein an input terminal of the power conversion circuit is configured to connect to at least one photovoltaic string, each of the at least one photovoltaic string comprises at least one converter and a photovoltaic module corresponding to each converter, and an input terminal of each converter is connected to the corresponding photovoltaic module; and the inverter controller is configured to: when an electric arc is detected between the at least one photovoltaic string and the inverter, control an input current of the inverter to decrease to extinguish the arc; and after the arc is extinguished, control an output voltage of the at least one photovoltaic string to decrease to a first preset voltage, wherein the first preset voltage is less than an input voltage of the inverter when the electric arc is detected; or control a maximum value of an output current of the at least one photovoltaic string to be a first preset current, wherein the first preset current is less than the input current of the inverter when the electric arc is detected.

15 . The inverter according to claim 14 , wherein the inverter controller is further configured to: after controlling the maximum value of the output current of the at least one photovoltaic string to be the first preset current, decrease the input voltage of the inverter to the input voltage of the inverter when the electric arc is detected.

16 . The inverter according to claim 14 , wherein the inverter controller is further configured to: after controlling the output voltage of the at least one photovoltaic string to decrease to the first preset voltage, increase the input current of the inverter to the input current of the inverter when the electric arc is detected.

17 . The inverter according to claim 14 , wherein each of the at least one photovoltaic string comprises at least two converters; and the inverter controller is further configured to send a current control instruction to each converter in the at least one photovoltaic string, to control a maximum output current of each converter in the at least one photovoltaic string to be the first preset current.

18 . The inverter according to claim 16 , wherein the inverter controller is further configured to: after no electric arc is detected within a preset time period after increasing the input current of the inverter to the input current of the inverter when the electric arc is detected, skip controlling the output voltage of the at least one photovoltaic string to decrease to the fi

Assignees

• Huawei Digital Power Tech Co Ltd

Inventors

• Liu Yongquan
• Gu Guilei
• Xiao Gang
• Zhu Dili

Classifications

• H02J2101/24

  Photovoltaics · CPC title

• Y02E10/50

  Photovoltaic [PV] energy · CPC title

• H02H7/1227 Primary

  responsive to abnormalities in the output circuit, e.g. short circuit · CPC title

• H02S50/10 Primary

  Testing of PV devices, e.g. of PV modules or single PV cells (testing of semiconductor devices during manufacturing {H10P74/00}) · CPC title

• H02S40/32

  comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules · CPC title